Development of technology for simultaneously recording (writing) and reading on a plurality of medium surfaces in a hard disk device is under way. Since this technology is able to increase the number of channels for recording and reading of data, it is useful for increasing a writing/reading transfer rate.
However, after media and recording (writing) heads are assembled into a hard disk device and a physical deviation of each recording head that accesses a medium surface is adjusted, additional relative recording head error between two medium surfaces may occur due to subsequent factors such as impact and thermal deformation. This additional relative recording head error between two medium surfaces is referred to herein as an “inter-plane relative trajectory error.” When mechanical measures are taken to address the inter-plane relative trajectory error caused by such factors, such as individually adjusting the positions of the recording heads, the number of components in the hard disk device is increased, and the mechanical design of the hard disk device becomes significantly more complicated.